Carotenoids are currently under intense scrutiny regarding their potential to modulate chronic disease risk and prevent vitamin A deficiency, and renewed emphasis has been placed on achieving a better understanding of the metabolic fate of these compounds in humans. The development of new animal models, and use of human metabolic studies and stable tracer methods have greatly improved our knowledge of how carotenoids are absorbed, metabolized, and transported to tissues; however, many important issues remain unresolved. For example, intestinal uptake of carotenoids occurs by passive diffusion, but the lumenal or intracellular factors limiting this process are obscure. The intestinal mucosa plays a key role in the metabolism of provitamin A carotenoids such as beta-carotene, thus greatly influencing their bioavailability. Most recent evidence supports a central oxidation mechanism of cleavage of beta-carotene to retinal in the intestinal mucosa, but the extent and site(s) of postabsorptive metabolism in the human is unknown. While the human and other species clearly absorb non-provitamin A carotenoids, little is known of the extent and pathways of their metabolism and elimination. The metabolic fate of cis isomers of beta-carotene is a subject of recent interest, since 9-cis retinoic acid can apparently be formed from 9-cis beta-carotene in vitro and in vivo. Substantial cis-trans isomerization of at least small oral doses of 9-cis beta-carotene occurs in the human, although the site of isomerization is not yet known. Carotenoids are transported in plasma exclusively by lipoproteins, with the distribution among lipoprotein classes determined in large part by the physical properties of the carotenoid. The consequences of differential distribution in terms of tissue uptake and retention are not clear at present. Improved knowledge of the metabolic fate of carotenoids will assist in the development and testing of hypotheses regarding their potential to influence biological processes in the human.

A model-based predictive control algorithm is developed to maintain normoglycemia in the Type I diabetic patient using a closed-loop insulin infusion pump. Utilizing compartmental modeling techniques, a fundamental model of the diabetic patient is constructed. The resulting nineteenth-order nonlinear pharmacokinetic-pharmacodynamic representation is used in controller synthesis. Linear identification of an input-output model from noisy patient data is performed by filtering the impulse-response coefficients via projection onto the Laguerre basis. A linear model predictive controller is developed using the identified step response model. Controller performance for unmeasured disturbance rejection (50 g oral glucose tolerance test) is examined. Glucose setpoint tracking performance is improved by designing a second controller which substitutes a more detailed internal model including state-estimation and a Kalman filter for the input-output representation. The state-estimating controller maintains glucose within 15 mg/dl of the setpoint in the presence of measurement noise. Under noise-free conditions, the model-based predictive controller using state estimation outperforms an internal model controller from literature (49.4% reduction in undershoot and 45.7% reduction in settling time). These results demonstrate the potential use of predictive algorithms for blood glucose control in an insulin infusion pump.

In egg-laying animals, mothers can influence the development of their offspring via the suite of biochemicals they incorporate into the nourishing yolk (e.g. lipids, hormones). However, the long-lasting fitness consequences of this early nutritional environment have often proved elusive. Here, we show that the colorful carotenoid pigments that female zebra finches (Taeniopygia guttata) deposit into egg yolks influence embryonic and nestling survival, the sex ratio of fledged offspring, and the eventual ornamental coloration displayed by their offspring as adults. Mothers experimentally supplemented with dietary carotenoids prior to egg-laying incorporated more carotenoids into eggs, which, due to the antioxidant activity of carotenoids, rendered their embryos less susceptible to free-radical attack during development. These eggs were subsequently more likely to hatch, fledge offspring, produce more sons than daughters, and produce sons who exhibited more brightly colored carotenoid-based beak pigmentation. Provisioned mothers also acquired more colorful beaks, which directly predicted levels of carotenoids found in eggs, thus indicating that these pigments may function not only as physiological 'damage-protectants' in adults and offspring but also as morphological signals of maternal reproductive capabilities.

In this work, several aspects of in vivo glucose detection using a nanotube-based optical sensor are considered. The optical properties of commonly used organic and nanoparticle fluorescent probes are compared with respect to quantum yield, human tissue penetration, and photobleaching stability. The latter two factors are shown to dominate sensor viability and require a near-infrared nanoparticle fluorophore for practical device operation. The dynamics of a model optical sensor are compared to a flux-measuring electrochemical sensor of equal area using a mathematical simulation of a healthy patient ingesting three predefined meals per day. Both sensors demonstrate an approximately linear response to blood glucose levels. It is shown that the optical sensor, which transduces glucose concentration, not flux, directly is significantly more stable to membrane biofouling.